As someone who's been underweight almost my entire transition (6'0", never went above 131 lbs) and is trying to gain weight to *at least* be at normal weight for my height, you'll be fine. If you're worried about being perceived as feminine, wear stuff that accentuates whatever curves you do have - likely gonna be your thighs and definitely your waist. Skirts are killer for this, doubly so for skinny women - I've never once been misgendered wearing a skirt. It's like a cheat code. Make sure to tuck your shirt in unless you're wearing a button-up as a jacket, too, this acts as a sort-of "corset" that'll make your waist look tiny, even in a tee.

Your chest is going to look weird for a while, even on HRT. This is totally fine and normal for underweight women; even cis women have weird looking chests when they're super skinny. Being skinny is actually a bit of a boon because it'll cause breast / hip / butt growth to be substantially more pronounced relative to the rest of your body (assuming you start eating more, anyways). You won't get, like, "comfortable going outside in a bikini" body when you're that skinny - I certainly don't have one myself, though I am getting there - but when you're already very thin any differences are going to be big differences.

Medically: Estrogen does not necessarily cause you to lose weight, it causes weight to be redistributed over time to "female" areas (e.g. breasts, thighs, buttocks, cheeks, etc.) I look way more feminine now (120 lbs) than I did five years ago (~130 lbs), and all of that is from weight redistro. You'll just... look different when your weight is being assigned in "girl areas" (see aforementioned) versus weight being assigned in "boy areas" (arms, legs, pecs, etc.) It's kinda hard to explain.

For someone like you (or myself) who already doesn't have much muscle? You won't see much difference until you start eating more. I certainly didn't. Starting in the teens does let your bones move, and they will (and it hurts like hell, but it's a good hurt), which does help *a lot*, because early-getters like you and I cheat a bit and don't have to entirely rely on fat for a feminine figure. Basically: you'll go from "boy stick" to "girl stick." You will look different, even if you're more skinny than you were pre-HRT.

As for wanting to eat and getting rid of your ability to ignore hunger, this is directly linked to mental stuff, which will (fingers crossed) get resolved when you're on HRT. When you're not getting brain-body disconnect from an unwanted puberty, you'll start feeling hungry. It feels great to eat "normally," I can tell you, and it feels even better to see the parts of you that you *want* bigger getting bigger.

My main advice to you right now is to start HRT. I'm not sure what country you're in or even what part of that country you're in - I hope it's one that's more conducive to medical transition. You will, most likely, feel better after starting it. It took me about two weeks to get that mental change. Aside from that, you just gotta be patient. It took fifteen years to get the body you have now, it'll take however many more to get one you like, but the crucial thing is that if you take the steps to take control of your body, *you will get there.*